Changelog:
Upgrade point
This is a late version, ZUI 4.0, thank you for your patience. This update brings new key elements such as new lock screen, game mode, payment security, etc., as well as intimate functions such as “Zhengya” theme, sleep monitoring, nighttime extreme power saving, website security monitoring, and recovery of pre-installed applications. Improved the game's stuck problem and a lot of detail optimization. Long-term polishing, only for you.
Precautions:
Make sure your phone doesn't have a root and has plenty of power and storage. It is recommended that you reboot the system again after the upgrade is complete. If you encounter any problems during the upgrade process, please go to the Lenovo official forum (https://club.lenovo.com.cn/phone) for support, or let us know by "I want feedback."
During the upgrade process, the phone will heat up; for the first time after the upgrade, there may be a short-term slow response or increased power consumption. These are normal conditions, please don't worry.
ZUI 4.0 upgrade points
Desktop and system interface
New full-screen lock screen, please turn left on the lock screen to open the carousel, and also collect and share your favorite lock screen wallpaper;
Add the theme of “Zhengya” to give you a different feeling;
Optimize the interactive display of contacts and caller interfaces;
System and security
Add payment security to give you a secure and independent payment environment;
Added recovery pre-installed application function, uninstalled application one-click recovery;
Add a new game mode to fully optimize the game environment, shield unrelated interference, and help you to fully participate in the game state;
New Xunfei input method ZUI customized version, support game keyboard mode, play more convenient while playing;
Added URL security monitoring, prompting suspicious fake website, giving you a pair of eyes!
Adding extreme power saving at night, strictly controlling unnecessary self-starting power consumption behavior when you sleep well;
Optimize rights management and application installation strategies, and the system is more secure;
Optimize the harassment interception mechanism to improve call interception efficiency;
Optimize game jackpot issues and improve the gaming experience;
U health
Add sleep monitoring and sleep reminder, ZUI is your sleep housekeeper;
calendar
Increase festival details and learn more about solar terms and festivals;
Main interface optimization, adding more details;
Add new app
Adding Lenovo APP, it is more convenient for mobile phones to access official forums

This update brings new key elements such as new lock screen, game mode, payment security, etc., as well as intimate functions such as “Zhengya” theme, sleep monitoring, nighttime extreme power saving, website security monitoring, and recovery of pre-installed applications. Improved the game's stuck problem and a lot of detail optimization. Long-term polishing, only for you.

ZUI 4.0 upgrade points desktop and system interface new full-screen lock screen, please turn left on the lock screen interface to open the carousel, you can also collect and share your favorite lock screen wallpaper; add "Zheng Ya" theme, square inch to give you Experience; optimize interactive display of contacts and caller interface; add security for system and security, give you a secure and independent payment environment; add pre-installed application function, uninstall application one-click recovery; add new game mode, fully optimize Game environment, shielding unrelated interference, help you to fully participate in the game state; new Xunfei input method ZUI customized version, support game keypad mode, play more convenient while chatting; add URL security monitoring, prompt suspicious fake website, give You have a pair of eye-catching eyes; add the ultimate energy saving at night, strictly control unnecessary self-starting power consumption behavior when you sleep well; optimize the rights management and application installation strategy, the system has more peace of mind protection; optimize the harassment interception mechanism and improve the efficiency of call interception; Optimize the game Caton problem and improve the game experience; U Health adds sleep monitoring and sleep reminder, ZUI is your sleep housekeeper; calendar increase Festival information, learn more solar terms and festivals little knowledge; the main interface optimization, add more details; application to add new Lenovo APP, more convenient mobile access to the official forum.

New Member

I found the ota update file on a russian site (googled the 4.0.233st for z2121) but was unable to install it. Inside .zuiota or in root directory update.zip . Seems like it starts installing and after 2% it gives an error, so i reboot to phone mode.